This invention relates to a leakage gas recirculation system for use in a Stirling engine, more particularly to a pumping device to return leaked gas into a cylinder chamber of a Stirling engine.
Stirling engines have received increasing attention in recent years owing to their high torque characteristics, clean exhaust gas, low noise, low fuel expense, low maintenance, and high durability as compared with a conventional gasoline engine. Furthermore, the thermal efficiency of a Stirling engine are equal or superior to those of the internal combustion engine because in a Stirling engine hydrogen or helium is used as the working fluid instead of air, whereby the temperature efficiency of the thermal heat exhangers are greatly improved.
However, since the hydrogen or helium working fluid has relatively small molecules, it is difficult to properly seal a Stirling engine. Stirling engines have exhibited high leakage in the sealing area between the cylinder wall and the piston rod. Conventional "roll-sox" seals are reasonably effective but their durability is low due to the materials used therein.
In a recent trials, multiple seal rings are used to form a block seal portion, whereby the pressure of the working fluid is first reduced therein, so that seal durability is greatly enhanced. For the perfection of the sealability at the block seal portion, some plans or conceptions have been developed for returning the working liquid leaked from the block seal portion into the cylinder chamber of a Stirling engine. However, this is very difficult to accomplish effectively due to the lack of a suitable mechanism therefor.